Method for interconnecting successive sections of walls and partitions cast in the ground



Jan. 21, 1969 J. COURTE 8,422,627

METHOD FOR INTERCONNECTING SUCCESSIVE SECTIONS OF WALLS AND PARTITIONS CAST IN THE GROUND Filed March a, 1965 sneei; I of :s 2 2 Lyra/roe J4 coves 00mm- BVWUMM Jan. 21, 1969 J. COURTE 3,422,627

METHOD FOR INTERCONNECTING SUCCESSIVE SECTIONS OF WALLS AND PARTITIONS' CAST IN THE GROUND Filed March 8, 1965 Sheet 2 of 5 Fig.6 A 78/Z'1ZC7$ B V r v mm 'IIIIIIIIIIIIIIIIIIIA Jan. 21, 1969 J. COURTE 3,422,627

METHOD FOR INTERCONNECTING SUCCESSIVE SECTIONS OF WALLS AND PARTITIONS CAST IN THE GROUND 7 Filed March 8, 1965 Sheet 3 of 8 .JQWSJM Arr-v.

Patented Jan. 21, 1969 US. CI. 6135 10 Claims Int. Cl. E02d 5/10; E0211 27/ 00; E04g 23/00 ABSTRACT OF THE DISCLOSURE A method for executing cast walls made of successive elements cast down to a considerable depth consisting in providing a recess extending throughout the height of each successive cast element over a fraction of its breadth, setting a cylindrical tube inside said recess during the casting of the next element. The tube being removed, the recess is washed and filled with concrete after testing the fluidtightness between the cooperating cast elements.

Various methods exist for casting the successive sections of a wall or partition of concrete or the like material inside a pit formed in the ground.

According to known methods, an elongated pit is first formed, the breadth and depth of which pit are equal to that of the underground wall it is desired to cast.

In order to prevent the walls of said pit from collapsing, a filling constituted by a so-called mud liquid is caused to be present throughout the duration of the digging of the pit.

Said mud is constituted by a suspension of clay in water with a possible incorporation of various reagents or fillings showing thixotropic properties. Said suspension holds the walls of the pit in position by reason both of its specific weight and of the formation of a waterproofing deposit or cake over said walls.

When the desired depth of pit is reached, the latter is filled with concrete or the like suitable material. Said filling is performed underneath the mud, the filling beginning at the bottom of the pit while various methods are resorted to which prevent the cast material from being soiled by the mud.

Such underground walls are if required reinforced, in which case the reinforcing irons are positioned after the pit has been dug completely and before the concrete is cast into said pit.

Certain technical requirements and chiefly the throughput of the concrete casting means require in practice a limitation in the length of the pit. For this reason, the execution of very long walls is performed by means of successive sections or panels arranged in succession and in alignment.

Obviously the connecting surface between two successive elements or sections leads to a risk of discontinuity in the finished wall.

The underground walls thus obtained serve generally as fluidtight or carrier means or else both as fluidtight and carrier means so that special care should be taken for the execution of the joints between its successive sections.

My invention has for its object a method and means for improving the connection between the successive sections or panels while ensuring the continuity of the underground wall both as concerns fluidtightness and the transmission of stresses.

In order to provide a better disclosure of my invention, I will refer first to the execution of two successive wall sections according to a known prior method, with the use of a circular boring tool for the formation of the FIGS. 1, 2 and 3 illustrate diagrammatically from above the successive stages of the execution of such a wall according to the known prior method.

FIG. 1 shows the execution of a first or primary section for which two cylindrical bore holes are first executed in a vertical direction as shown at 1 and 2, the diameters of said bore holes being equal to the thickness of the wall to be executed and the depth slightly superior to that of said proposed wall, said bore holes defining the ends of the first section to 'be produced. The pit is then dug out for said section by slicing the earth horizontally in successive operations between the two bore holes 1 and 2 until the desired depth is reached.

If as is generally the case, the earth is not sufiiciently cohesive for the walls of the pit to be self supporting, two smooth cylindrical tubes 4 and 5 called stop-end tubes are then introduced at the two ends 1 and 2 of the pit in a vertical direction as obtained through known means, the diameter of which tubes approximates the thickness of the pit obtained; said tubes are sunk down to the bottom of the bore holes, which means slightly deeper than the bottom of the pit; this method allows maintaining the vertical direction of tubes 4 and 5 during the subsequent casting of the pit 3. The pit 3 is then filled with concrete in its portion extending between the stop-end tubes 4 and 5. Lastly, when the concrete has set to a sufficient extent, the tubes 4 and 5 are removed and leave in the cast concrete a smooth vertical geometrical half cylindrical surface or joint the diameter of which is equal to that of the stop-end tubes.

FIG. 2 illustrates the execution of a second or secondary element or panel following the first or primary panel thus cast in the ground. Said primary element of the wall appears in accordance with the method disclosed as an elongated section A bounded at 1 and 2 by concave joint surfaces corresponding to one half periphery of the precedingly removed stop-end tubes 4 and 5.

The original bore hole 2 forms one of the cylindrical bore holes necessary for the casting of the second wall panel and the execution of a further terminal cylindrical bore hole at 6 is therefore suflicient.

The digging and the filling with concrete of the secondary section B of the pit are executed in the same manner as for the primary section. However, only one stop-end tube is inserted during the filling with concrete, which tube is inserted in the outer bore hole 6 since the concayle end of the primary panel closes the mold at the en 2.

FIG. 3 illustrates the wall element obtained after the filling with concrete of the secondary section or panel B. The two successive panels or elements A and B are thus in contact with each other along a joining surface or joint extending over a half cylinder having a vertical axis. Such a shape provided for a joining surface is advantageous since the elements interengage each other.

Now, as mentioned hereinabove, the digging and filling with concrete are executed while the pit is filled with mud. The mud forms a clayey deposit of cake on the walls of the pit which cooperates in the proper behavior of said walls. But said deposit is also obtained on the concrete wall in contact with the mud and in particular, a clay deposit is obtained during the digging of the pit section B on the terminal surface of the first wall section A at 2. Generally care is taken to scrape said surface before filling concrete into the pit section B so as to remove to the utmost said clayey deposit, but it is never possible to ascertain whether said removal is actually complete.

The presence of a residual fluidtight cake between two successive concrete elements does not show any actual drawback if the underground wall serves only as a fluidtight member and if the difference in the hydraulic heads on the two surfaces of the wall is not considerable.

On the contrary, if the difference in head is large, the pressure of the water may drive the cake away so that a leak appears between the wall elements A and B. Furthermore, if the wall is to play the part of a carrier mem-- ber, such a cake forms a point of lesser resistance which prevents any proper transmission of the stresses. These drawback are actually disturbing only for operation at comparatively considerable depths, say beyond 8 or meters under ground level.

My invention has for its object a method and means which remove said drawbacks. It chiefly consists in providing in proximity with the joining surface or joint through means to be described hereinafter, a key recess which allows checking the condition of said joint and obtaining perfect fiuidtightness while furthermore it improves the interdependence between the successive elements of the Wall by a filling of concrete in the key recess cut through them with a view to forming an actual unit constituted by said elements. In fact, said key recess being closed throughout its periphery may be readily cleaned with clear water so that the concrete when filling said key recess adheres perfectly to the precedingly cast concrete elements and ensures between them a connection through a sort of cast key or core which may be reinforced by iron members.

The accompanying drawings illustrate my invention, to wit:

FIGS. 1 to 3 relate to a conventional method as described hereinabove.

FIGS. 4 to 7 are diagrammatic plan views of different embodiments of my invention selected by way of example.

FIG. 8 illustrates a method for removing the tubes serving for the execution of my invention.

FIG. 9 illustrates the removable stud resorted to for this method.

FIGS. 10 to 13 illustrate still further embodiments of my improved method.

Turning first to FIG. 4, there is inserted, after casting the concrete of the primary section A and after digging the location of the secondary wall section B still full of mud, a smooth vertical key tube 7 in contact with the medial section of the joint surface C of the primary section, the diameter of said key tube 7 being clearly smaller than the breadth of the wall to be executed, said diameter being advantageously equal to 180 mm.

The verticality of the tube 7 should be checked by means of a plumb rule in accordance with the well-known method which is quite sufiicient for the purpose. According to a preferred procedure, the tube may be set in the desired vertical position by rigidly securing it to the iron reinforcements or even by resorting to a mere guiding member which may in fact be removed. Thus, the tube may engage the joint surface C along its medial generating line. Furthermore, the concrete used for filling the section B urges through its mere longitudinal pressure the cylinder 7 against said joint surface C and holds it along said medial generating line as a result of lateral inertia. Lastly, in order to define perfectly the vertical position of the tube and to prevent any possible raising of the tube 7 during the filling of the pit with concrete, it is possible to cast, after positioning the tube 7 and before the casting of the concrete, a predetermined amount of sand, for instance, into the tube 7, so as to form at the lower end of the tube both a weight which prevents any shifting of the latter and a plug opposing the possible rising of the concrete inside said tube through the lower end of the latter. When the section B has been cast and has set, the key tube 7 is re moved, which leaves in position a vertical cylindrical key recess 8 full of mud. Said recess may if required be bored by means of a percussion tool so as to be enlarged up to the circle drawn in interrupted lines and to cut through the joining surface C. It is then sufficient to inject under pressure clear water into said recess or else to empty it if 4 the wall is bathed by a sheet of water so as to check whether the joint is already fluidtight.

If the joint is fiuidtight or allows only water to flow without this water carrying along any material removed from the ground layers, it is sufiicient to wash the walls of the recess when filled with clear water by using for instance a circular metal brush assuming a reciprocatory movement after which concrete is cast into the recess.

If, in contradistinction, water can flow through the joining surface and carries along with it particles of ground layers, the same operations as those referred to in the preceeding paragraph should be executed no longer under clear water but preferably under a light sludge filling.

If the joint is not fluidtight, it is possible to use said key recess associated if required with a grout pipe so as to inject under pressure a suspension of cement to fill the joint and to ensure its perfect fiuidtightness or else to use the key recess in order to form underneath the mud a cast concrete core or key.

FIG. 5 illustrates a joining surface or joint executed in a similar manner, but in which the inserted key tube 9 has a diameter which is almost equal to the thickness of the wall. After cleaning the joint surface and possibly after boring again so as to obtain a slightly larger diameter 10 for the key recess, said recess designated by 11 and extending at the desired location of the tube 9 is filled with a high grade concrete which may possibly be reinforced or be expansible. I thus obtain a core or rotula adapted to absorb the compressional or tensional stresses chiefly in the case-of circular Walls.

According to a development of my invention, it is possible to provide a recess 8a in the panel A before producing the recess 8b illustrated in FIG. 6. This forms two cylindrical recesses tangent to each other along the joining surface C, which recesses are filled with concrete simultaneously after cleaning thereof and production of a common uniform oval cross-section as shown by the dotted line 12 upon cutting off the two projections 12.

The procedure is advantageously as follows: there is secured. to the stop end tube 5 such as that shown in FIG. 1 a key tube 7a and this assembly is introduced into the pit so that the contacting line between the tubes may lie in the medial plane of the wall to be executed. These tubes are assembled at their upper ends by means of a readily removable bolt inserted at a point at about 0.80 m. above their lower ends which are filled with gravel over a height of say 0.50 m. The stud shown at 13 in FIG. 8 and separate in FIG. 9, is held in position on the side engaging the tube 71) by a pin 14 while its head 15 is urged inwardly of the tube 812 'by a spring 16. A cable 17 controlled from ground level is attached to the pin which allows tearing out said pin 14 whereupon the stud projected away from its former position by the spring 16 is recovered through the agency of the auxiliary cable 18. This is done after filling with concrete the first panel. It is then an easy matter to disconnect the bolt at the upper ends of the tubes so as to remove independently both the larger stop end and the key tube which leaves a panel of the shape illustrated on the left hand side of FIG. 6 in which a recess 8a has been formedv within the joint surface. After digging out the pit for the panel B, the recess 8b is formed by means of a key tube 712 inserted tangentially with reference to the recess 8a formed in the panel A, the axes of the two recesses lying in the medial plane of the wall to be executed. This is obtained readily by rigidly securing said tube 7b to a guiding tube which is introduced into the previously formed recess out of which the key tube 7a has been removed. To ensure the desired vertical centering and. positioning of the key tube 7b for the panel B as required for the formation of the recess 8/), the tubes 7/) and 7c are secured together through a mere bolting at their opposite ends or in the case of deep pits in the manner described hereinabove by a bolt at their upper ends and a pin at their lower ends. In the first case, the lowering and subsequent removal of the tubes which are rigidly secured together, are performed by means of a crane. In the second case, the lowering is performed again by means of a crane and the removal is obtained by the same means, but independently for the two tubes after release of the bolt pin and stud. In both cases, the guiding tube 7c should have a diameter slightly less than the tube 7a which had formed the recess 811 so as to readily enter said recess. Cdncrete is then poured into the pit to form the panel B, the tubes 7b and 7c preventing the concrete from entering the corresponding recesses. After setting of the concrete, the tubes 7b and 7c are removed in the manner disclosed. After removal of the tubes, the cake extending over the walls of the recesses 8a and 8b is advantageously removed by an emulsifier. If this is not suflicient, each of the recesses is swept in its turn by flue brushes operating in the recesses in alternation with the emulsifier.

The shape then assumed by the joint surface C is that illustrated in FIG. 7 showing the recesses 8a and 81) opening into each other through the restricted opening defined by the concrete projections or tongues 12' which may be cut off by a boring bit. An oval cross-section 12 being then obtained, concrete is cast into the dual recess defined by said oval cross-section after checking of the fluidtightness of said recess, cleaning thereof and laying if required of a suitable reinforcment.

FIGS. 10 and 11 illustrate two stages of a modified operation adapted to ensure the assembly between the successive wall sections by keys or cores adhering to said sections. FIG. 10 is a plan view showing the arrangement used for the casting of the concrete of a primary section A. After digging out of the pit which is to be filled with said section, I position in accordance with the prior method, the terminal tube 5 and furthermore, in accordance with a modification of my invention, one or more smooth tubes 5 to the rear of the tube 5. A reinforcing cage illustrated diagrammatically by the iron member 23 is then caused to sink into the pit. Said reinforcing cage may include a loop 24 extending to either side of the tubes 5' so as to hold them in position after the casting of the concrete and when the concrete has begun to set and the tubes 5 and 5' are removed.

FIG. 11 shows how the next section B or secondary panel may be cast. As in the case of the primary section A, one or more smooth tubes 5" are sunk into the pit after removal of the tube 5 and before any casting of the secondary section; said smooth tubes 5 may be guided and held in position by a loop 25 formed by a further reinforcing cage 26 adapted to reinforce the secondary section or panel B.

After the casting of the section B and removal of said tubes 5", there remains between the two sections A and B a succession of cylindrical recesses. With a tool such as a boring bit, the tongues separating these recesses are broken as in the case of FIGS. 6 and 7 so as to produce a single continuous recess 27. The latter which is closed throughout its periphery may be readily cleaned as already described after which it is filled with concrete after insertion of reinforcing irons 28.

FIGS. 12 and 13 illustrate a further embodiment which allows reaching a similar result.

FIG. 12 is a plan view of the means resorted to in such a case for the filling of concrete into the primary section A of the pit. Said means include in addition to the terminal tube 5 an elongated casing 29. Said casing located to the rear of the tube 5 may be rigidly secured to the latter or else, as illustrated, it may be fitted on said tube through the agency of a slideway 30 along which it may slide vertically or again the casing may be independent of the tube and merely urged against it. After positioning of the reinforcements 31 and casting of the concrete A and when the concrete has begun to set, the tube 5 and the casing 29 are removed independently or else simultaneously if they are rigidly secured to each other.

FIG. 13 shows the means serving for the filling with concrete of the secondary pit section B.

After digging out said pit section B, an elongated casing 32 is inserted with a portion of its length engaging the recess formed in the wall element A by the then removed casing 29, the casing 32 being guided inside said recess. The casing 32 may carry a butt joint projecting to either side thereof so as to engage the terminal surface of the wall element A.

After positioning the reinforcements 34 adapted to hold the casing 32 in position and casting concrete into the pit section B and when the concrete has begun setting, the casing 32 is removed.

The recess obtained at the location of the casing 32 may be cleaned as described hereinabove and filled with concrete after reinforcing irons have been inserted if required as in the preceding cases.

The method last disclosed ensures a connection between successive wall elements by means of a girder of reinforced concrete adhering perfectly to the concrete of both elements While the overlapping of its armatures with reference to those incorporated with the two :wall elements provides the actual mechanical continuity of the wall.

Of course the embodiments described have been given solely by way of examples and it is possible without widening the scope of the invention as defined by the accompanying claims, to modify the arrangements used for the formation of the recesses as also the shape, size, number or position of these recesses and consequently of the connecting girders.

In particular in the case of an incurved or polygonal Wall, -I may use tubes or casings matching the outline of the wall to form the inner recesses.

Similarly, according to the distribution of the stresses in the wall, the connecting girder may be located nearer the tensioned surface of the wall or else connecting girders may be formed in the vicinity of each surface of the wall.

My invention is applicable to all cases of execution of a wall or partition through methods which may dilfer from that described with reference to FIGS. 1 to 3, since the stop-end tubes are not always essential in the case of coherent grounds as mentioned hereinabove.

In particular I may execute the preliminary digging out of the ends of each pit section with tools other than ciroular boring tools, such as a shovel or a skip adapted to produce a flat transverse surface. Lastly the recesses may be executed in any desired manner, for instance by means of yielding inflatable tubes. :It is even possible to fonm them after the setting of the corresponding successive lwall elements, for instance by boring.

What I claim is:

1. In a method for executing an underground structure constituted by a horizontal succession of joining underground wall elements, the steps consisting in casting the different elements in situ, inserting to the front of the free transverse surface of each cast element facing the location of the next adjacent element to be cast and throughout the height of said elements a cylindrical tube extending at least up to said transverse surface symmetrically with reference to the lateral surfaces of the elements, casting said adjacent element in joining relationship with the first-mentioned cast element, removing the tube, washing first the location of the tube, testing fiuid tightness and then filling it with concrete.

2. In a method for executing an underground structure constituted by a horizontal succession of joining underground wall elements, the steps consisting in casting the different elements in situ, inserting to the front of the free transverse surface of each cast element facing the location of the next adjacent element to be cast and throughout the height of said elements a cylindrical tube extending at least up to said transverse surface symmetrically with reference to the lateral surfaces of the elements, casting said adjacent element in joining relationship with the first mentioned cast element, removing the tube, washing first the location of the tube testing fluidtightness and then filling it with concrete under slight sludge.

3. In a method for executing an underground structure constituted by a horizontal succession of joining undergnound wall elements, the steps consisting in casting the different elements in situ, inserting to the front of the free transverse surface of each cast element facing the location of the next adjacent element to be cast and throughout the height of said elements a cylindrical tube extending at least up to said transverse surface symmetrically with reference to the lateral surface of the elements, the diameter of said tube being clearly smaller than the breadth of the elements, casting said adjacent elements in joining relationship with the first-mentioned cast element, removing the tube, washing first the location of the tube testing fluid tightness and then filling it with concrete.

4. In a method for executing an underground structure constituted by a horizontal succession of joining underground wall elements, the steps consisting in casting the successive elements in situ, preparing in registry with each transverse surface of each element to be cast respectively and throughout the height of said elements a cylindrical recess stopping short of the lateral surfaces of said elements, each element being cast in joining relationship with the precedingly cast element with a spacing constituted by the recesses formed to either side of the transverse surface between the elernent thus cast and the precedingly cast element, cutting through the concrete between the recesses formed between said elements and filling concrete into the compound recess formed by last mentioned recesses.

5. In a method for executing an underground structure constituted by a horizontal succession of joining underground wall elements, the steps consisting in casting in succession the different elements in situ, inserting in the location of each of them a cylindrical vertical tube in registry with each of the transverse surfaces of said location facing the precedingly cast element and the loation of the next adjacent element to be cast and throughout the height of said elements, the diameter of said tubes being clearly smaller than the breadth of the elements, casting the element between the tubes thus inserted, removing the two tubes to either side of the transverse surface separating the element thus cast from the precedingly cast element, cutting through the concrete between the recesses formed by the removal of said tubes and filling concrete into the compound recess formed by said recesses.

6. In a method for executing an underground structure constituted by a horizontal succession of joining underground wall elements, the steps consisting in forming in succession the pits into which the successive wall elements are to be cast, inserting a stop-end tube defining the free end of each element to be cast, said stop-end tube being tangentially and detachably secured to a tube of a smaller diameter standing on the side of the stop-end tube facing the location of the element to be cast, casting said element between the previously cast element and said tubes, releasing from ground level the connection between the two tubes, removing said stop-end tube and smaller tube independently, introducing into the locations of the two tubes respectively two tangentially and detachably interconnected tubes of diameters almost equal to that of said smaller tube, the axes of which lie in a plane parallel with the sides of the cast element, forming the next cast element in the same manner as the element which has been cast, disconnecting from ground level last-mentioned tubes, removing the latter, breaking through the concrete to ensure communication between the recesses defined by last-mentioned tubes and filling with concrete the compound recess obtained.

7. In a method or executing an underground structure constituted by a horizontal succession of joining underground wall elements, the steps consisting in forming in succession the pits into which the successive wall elements are to be cast, inserting a stop-end tube defining the free end of each element to be cast together with at least one further tube of a smaller diameter standing on the side of the stop-end tube facing the location of the element to be cast, said tubes being tangent to each other in the medial longitudinal plane of said element to be cast, inserting a reinforcement holding said tubes in position, casting the element to be cast between the previously cast element and said tube, removing said tubes, inserting at least one vertical cylindrical tube in the location of the next element to be cast, the successive last-mentioned tubes being tangent to each other and to the terminal surface of the previously cast element in the medial longitudinal plane of said next element to be cast, inserting a reinforcement holding said tube in position, forming the next cast element in the same manner as the element which has been cast, removing last-mentioned tubes, smoothing out the compound recess formed by the retrnoval of the tubes in the first-mentioned and next element to form a recess with substantially fiat sides, cleaning said compound recess and casting concrete into same. 8. In a method for executing an underground structure constituted by a horizontal succession of joining underground wall elements, the steps consisting in forming in succession the pits into which the successive wall elements are to be cast, inserting a stop-end tube defining the free end of an element to be cast, together with a horizontal elongated casing extending throughout the height of the element to be cast between the stop-end tube and a point within the element to be east along a line parallel with the longitudinal axis of said element, said casing lying at a distance from the lateral surfaces of said elements, casting the element to be cast between the previously cast element and said tube and casing, removing the tube and casing, inserting in the recess formed by the casing in the cast element a further longer casing extending throughout the height of the element and projecting clearly into the location of the next element to be cast in parallelism with the lateral walls of the latter, forming the next cast element in the same manner as the element which has just been cast, removing last-mentioned casing, cleaning the recess formed by the latter and filling it with concrete.

9. In a method for executing an underground structure constituted by a horizontal succession of joining underground wall elements, the steps consisting in forming in succession the pits into which the successive wall elements are to be cast, inserting a stop-end tube defining the free end of an element to be cast together with a horizontal elongated casing extending throughout the height of the element to be cast between the stop-end tube and a point within the element to be cast along a line parallel with the longitudinal axis of said element, said casing lying at a distance from the lateral surfaces of said element, casting the element to be cast between the previously cast element and said tube and easing, removing the tube and casing, inserting in the recess formed by the casing in the cast element a slightly smaller casing, casting the next adjacent element, removing the smaller casing, cleaning the recess, testing and perfecting the fluid tightness of the joint between the first-mentioned and next adjacent elements and filling the recess with concrete.

1!). In a method for executing an underground structure consituted by a horizontal succession of joining underground wall elements, the steps consisting in forming in succession the pits into which the successive wall elements are to be cast, inserting a stop-end tube defining the free end of an element to be cast, together with a horizontal elongated casing extending throughout the height of the element to be cast between the stop-end tube and a point within the element to be cast along a line parallel with the longitudinal axis of said element, said casing lying at a distance from the lateral surfaces of said element,

9 10 casting the element to be cast between the previously cast 1,628,933 5/ 1927 Troiel 52-742 X element and said tube and casing, removing the tube and 2,411,011 11/1946 Troiel 52744 X casing, inserting in the recess formed by the casing in the 2,644,997 7/1953 Billings 52586 X cast element a further longer casing extending throughout 2,791,886 5/ 1957 Veder 6139 X the height of the element and projecting clearly into the 5 3,310,952 3/1967 Veder 61 35 location of the next element to be cast in parallelism with the lateral walls of the latter, forming the next cast FOREIGN PATENTS element in the same manner vas the element which has 662,458 12/1951 Great Britain just been cast, removing last-mentioned casing, cleaning the recess formed by the latter, inserting reinforcing irons 10 ALFRED G. PERHAM Primary Examiner in said recess, and filling it with concrete.

References Cited US. Cl. X.R.

UNITED STATES PATENTS 52 1 9 742; 1 59; 2 4 34 784,925 3/1905 Crawford 52-744 15 

